C#: Reducers and types with same name but different capitalization have bad error text

If you have a module with following table and reducer, there are no errors in IDE, but publishing returns a fairly unhelpful error

[Table]
public partial class Test { }

[Reducer]
public static void test() { }

Publishing error:

CSC : warning CS8785: Generator 'Module' failed to generate source. It will not contribute to the output and compilation errors may occur as a result. Exception was of type 'ArgumentException' with message 'The hintName 'Module.test.cs' of the added source file must be unique within a generator.
CSC : error CS5001: Program does not contain a static 'Main' method suitable for an entry point

Note: This can also happen with two reducers or two tables - it doesn't need to be a combination of both.

Start by reproducing the sample module with a table and reducer whose names differ only by capitalization, then trace the C# module source generator used during publishing. Confirm the duplicate hintName error and identify the generator entry point responsible; done means publishing this case no longer produces that error, including when both items are reducers or tables.